MGN RDRS Compressed Basic Image Data Record (CBIDR)
CBIDR – Compressed Basic Image Data Record
Instrument: Magellan Radar System
PDS Data Set ID: MGN-V-RDRS-5-C-BIDR-V1.0 DOI: 10.17189/1522526
For more information about RDRS CBIDR products, see the CBIDR Data Set Description and CBIDR Product SIS.
The Radar System (RDRS) Compressed Basic Image Data Record (CBIDR) data products consist of synthetic aperture radar (SAR) image data acquired along one orbit. Pixel widths are 225 m. Data are presented as 8-bit pixel brightness values where the brightness is in proportion to the scaled radar backscatter cross section. Scaling is accomplished by dividing the radar cross section value for each pixel by the value estimated from the Muhleman Law for the mid-range point incidence angle, converting the ratio to decibels, and scaling to a 1 to 251 output range. The 1 value corresponds to -20 dB and 251 to +30 dB, with a linear quantization of 0.2 dB in between. Data have at least 4 looks.
CBIDRs are presented as image files containing two 2-byte VAX integers at the beginning of each line. The first integer specifies the pixel offset to (# bytes to but NOT including) the first valid pixel; the second specifies a pointer to (# bytes to AND including) the last valid pixel. The remainder of the line consists of scaled backscatter cross section values.
Regions within 89 degrees of the equator have CBIDRs in sinusoidal equal area projection; CBIDR data located more than 80 degrees from the equator are also in oblique sinusoidal equal area projection. For the sinusoidal equal area projection, the origin is at 0 degrees latitude and the central meridian is the sub-spacecraft longitude at the equator, adjusted to the nearest multiple of 225 m, relative to a pixel centered at 0 degrees longitude.
RDRS CBIDR product subdirectories have the following directory names:
Cnnnn_vv
where:
nnnn = 4-digit decimal number denoting the Magellan Project-assigned orbit number
vv = the version number inherited from the original Full-Resolution BIDR (FBIDR) product from which the CBIDR was made
In ODE, CBIDR products, which include the files in the table below, have the following product IDs:
CBIDRcNNNN_VV (orbits 0376-3561)
IMX0NNNN;VV (orbits 3562-5747, 'X' equals 1 or 2)
Within each CBIDR product subdirectory, the following files appear. All files are .DAT unless otherwise identified, and all except the ERR file appear along with their corresponding PDS labels.
|
File Name |
File Contents |
File Type |
|
ERR.TXT |
Holds any error messages generated by the software that created the label files |
|
|
CLK |
SCLK/SCET conversion coefficients |
ASCII |
|
DCM |
Decommmutation and decalibration data |
ASCII |
|
DQS |
EDR data quality summary |
ASCII |
|
ENG |
Engineering data |
Binary |
|
EPH |
S/C ephemeris file |
ASCII |
|
HDR |
Orbit header |
ASCII |
|
IM1 |
Polar image data |
Binary |
|
IM1.AUX |
Polar image index file |
Binary |
|
IM2 |
Image data |
Binary |
|
IM2.AUX |
Image index file |
Binary |
|
MON |
DSN monitor records |
Binary |
|
OPF |
Orbit parameters |
Binary |
|
PBW |
Processing bandwidths |
ASCII |
|
PR1 |
Polar processing parameters |
Binary |
|
PR2 |
Processing parameters |
Binary |
|
QTN |
Quaternion pointing coefficients |
ASCII |
|
SAB |
Radar header records |
Binary |